A wireless local area network (WLAN) uses radio waves rather than wires to communicate between nodes. WLANs are flexible communication systems seen as an alternative to, or an extension of wired LANs. An access point is a hardware device that acts as a communication hub for users of a wireless device to connect to the LAN. Access points are important for extending the physical range of service in which a wireless user has access to the LAN. Access points also affect the throughput of the networks.
Wireless users are also known as client stations. Example client stations are personal computers operating with a wireless network card. The wireless network card may be compatible with the 802.11 standard, for example. An access point includes an antenna for sending forward link radio frequency signals to the client stations. The access point is also responsible for receiving reverse link radio frequency signals transmitted from each client station.
The most common type of antenna used to transmit and receive signals at an access point is an omni-directional monopole antenna. This type of antenna comprises a single wire or antenna element that is coupled to a transceiver within the access point. The transceiver receives reverse link signals transmitted from a client station, and transmits forward link signals to that client station.
The transmitted signals sent from a monopole antenna are omni-directional in nature. That is, the signals are sent with the same signal strength in all directions in a generally horizontal plane. Reception of signals with the monopole antenna element is likewise omni-directional. A monopole antenna does not differentiate in its ability to detect a signal in one direction versus detection of the same or a different signal coming from another direction. As a result, the antenna gain of an omni-directional antenna is generally low, resulting in a reduced range in which client stations can access the network via the access point. Moreover, the throughput of the network is adversely affected by low gain omni-directional antennas.